CVE-2026-80963

In the Linux kernel, the following vulnerability has been resolved:

dm-stats: fix a crash if allocation of per-cpu data fails

If "dm kvzalloc(percpu alloc size, cpu to node(cpu))" fails, the code jumps to the "out" label and calls dm stat free. dm stat free does "for each possible cpu(cpu) { dm kvfree(s->stat percpu[cpu][0].histogram, s->histogram alloc size);", which crashes with NULL pointer dereference if s->stat percpu[cpu] is NULL.

This commit fixes the bug by testing s->stat percpu[cpu] for NULL before using it.